Study on the Toughness Performance of Polypropylene Fiber and SBR Polymer Latex Modified Cement Mortar

In this paper, polypropylene fiber and SBR polymer latex are added into cement mortar to improve the toughness. Using two flexural toughness test methods of ASTM-C1018 and JSCE-SF4, the ratio of compressive strength to flexural strength (σC/σF for short) and flexural toughness index are used to evaluate the toughness of the cement mortar. The experimental results show that, comparing to the control cement mortar sample, when the SBR polymer mass percent of 20% and the polypropylene fiber volume percent of 1.0%, the σC/σF is 2.17, reduced by 59.2%, the ASTM toughness index I5, I10, I30 is 2.86, 2.95, 3.16 respectively, increased by 63.4%, 58.6%, 68.1% respectively, the JCI toughness index is 13.1, increased by 258%. Based on the SEM, adding SBR-polymer into cement mortar can form the polymer transition layer between the interfaces of polypropylene fibers and cement matrix, from XRD test, SBR polymer latex has no significant influence on the cement hydration after 7d curing. This research provides some useful references for the application of this new material.